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Re: The sperm secret operator: is it new?

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Yitzchak Scott-Thoennes
March 14, 2012 14:57
Re: The sperm secret operator: is it new?
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On Wed, Mar 14, 2012 at 7:48 AM, John Douglas Porter
<> wrote:
> So is that the Perl 6 smart match operator? or something else?

The latter.

> In any case... How does it work here?  It looks like it's functionally
> equivalent to scalar()... but why?

Perl's ~ is operand sensitive; if its operand has a numeric value
(either because it was assigned a number, the result of a numeric
operation,  or had been used in numeric context), it is a numeric
bitwise or (implicitly converting to UV, or under the scope of use
integer, IV, first); otherwise it is a string bitwise or.

For most inputs, in either case it can be repeated to reproduce the
original value and acts just like scalar().

Examples of exceptions:

# floating point

$x = 1.23; print ~~$x; # 1

# string used in numeric context

$x = "1.23"; print ~~$x if $x != 0; # 1

# integer out of range

use Config '%Config';

$x=2**(8*$Config{uvsize}); print ~~$x; # max uv

$x = -1; print ~~$x; # max uv

$x = 2**(8*$Config{uvsize}-1); use integer; print ~~$x; # min iv

$x = -2**(8*$Config{uvsize}-1)-1; use integer; print ~~$x; # min iv

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